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— Application to Lithium Iron Phosphate Cathode Material—
Shimadzu Review 78[3・4] (2021)
Previously, obtaining knowledge about changes in the chemical state of substances contained in cathode materials of lithium-ion batteries (LIB) mainly required the use of a synchrotron radiation facility. With the introduction of the XspeciaTM system, which is based on polychromatic simultaneous wavelength dispersive X-ray fluorescence (PSWDXRF) spectrometry, now chemical state changes can be easily observed in a laboratory. Thus far, we have used the Xspecia system to measure Mn, Co, and Ni compounds used in NCM ternary LIB cathode materials and to confirm there is a correlation between the formal oxidation number and the energy-shift in X-ray fluorescence peaks. We also successfully estimated changes in the valence state of the above cathode material elements during LIB charge-discharge cycles.
This article describes measuring the valence state in an LIB lithium iron phosphate (LFP) cathode material in order to investigate the possibility of using it as an alternative to NCM ternary cathode materials. As a result, Fe valence changes during the charge-discharge cycle were successfully observed as peak shifts similar to ternary cathode materials and relative valence changes in the Fe element were estimated using a nominal valence calibration curve.
1X-ray / Surface Business Unit, Analytical & Measuring Instruments Division, Shimadzu Corporation, Kyoto, Japan
2Advanced Analysis Unit, Technology Research Laboratory, Shimadzu Corporation, Kyoto, Japan
3Research Institute of Electrochemical Energy, Department of Energy and Environment, National Institute of Advanced Industrial Science and Technology (AIST), Osaka, Japan
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